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Corn Diseases - Bacterial Leaf Streak

 
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Bacterial Leaf Streak in Corn

Disease Facts

  • Caused by the bacterium Xanthomonas vasicola pv. vasculorum.
  • First identified in 2016 in Nebraska corn field.
  • Currently confirmed in 9 states: Nebraska, Colorado, Illinois, Iowa, Kansas, Minnesota, South Dakota, Oklahoma, Texas.
  • Can be found in field corn, seed corn, popcorn, and sweet corn.
  • Plant does not have to be injured for disease to enter the plant. Bacterium can enter plant through stomatal openings.
  • Bacterial inoculum overwinters on plant residue and causes symptoms on several host plants.
  • Many diseases look similar to bacterial leaf streak, so it is recommended to confirm disease through a diagnostic laboratory.
  • A different but closely-related pathogen affects sorghum; Xanthomonas vasicola pv. holcicola.
Map showing states with confirmed cases of corn bacterial leaf streak.

Symptoms and Impact on Crop

Symptoms

  • Narrow tan, yellow, brown, or orange lesions that have a bright yellow halo when backlit.
  • Lesions can extend to several inches long and stay in between leaf veins (interveinal).
  • Edges of the lesions are wavy and have a jagged appearance. This is one of the biggest distinguishing features from other diseases.
  • Lesions can also appear greasy or water-soaked.
  • Symptoms often appear on the bottom leaves of a plant and travel upwards. Can start in the upper canopy, often after large rain event.

Impact on Corn Yield

  • Extent of potential damage or yield loss is currently unknown.
  • Expected losses are minimal as long as extensive symptoms are not present before or during grain fill.

Bacterial Leaf Streak

Photo showing corn leaf with bacterial leaf streak.

Photo: Jennifer Chaky

  • Bacterial
  • Long lesions with a wavy edge.
  • When backlit, has a translucent appearance with a yellow halo.
  • Will exhibit bacterial streaming under a microscope.

Gray Leaf Spot

Photo showing corn leaf with gray leaf spot.

Photo: Steve Butzen

  • Fungal
  • Rectangular lesions that have very straight sides.
  • Light does not shine through easily (more opaque).
  • Can have dark, finger-like fungal structures.

Common Rust

Photo showing corn leaf with common rust.

Photo: Dan Wilkinson

  • Fungal
  • Often more oval or circular in shape.
  • Appears dark when leaf is backlit.
  • Lesions are raised above leaf surface.

Diplodia Leaf Streak

Photo showing corn leaf with diplodia leaf streak.

Photo: Jennifer Chaky

  • Fungal
  • Lesions are mostly oval to elongated.
  • Lesions have bright yellow edges, especially when backlit.
  • Often contains black pycnidia (fungal fruiting structures) imbedded in leaf tissue.

Southern Corn Leaf Blight

Photo showing corn leaf with southern corn leaf blight.

Photo: Gary Munkvold

  • Fungal
  • Lesions are rectangular to oblong in shape.
  • Appears tan in color.
  • Lack of uniformity makes it difficult to identify. Laboratory testing can help differentiate.

Factors Favoring Bacterial Leaf Streak

Weather

  • Warm conditions with a high relative humidity.
  • Can withstand cooler temperatures (different from gray leaf spot) and can be found as early as V4 in corn.
  • Thought to be spread by wind-driven rain and overhead irrigation.

Management Systems

  • More common in continuous corn fields but has been found in other rotation systems, particularly those that include another host crop.
  • Favored by minimum tillage systems where inoculum can remain on residue.

Plant species that display symptoms of bacterial leaf streak and are potential disease hosts:

  • Crops: Corn, oats, rice
  • Prairie Grasses: Big bluestem, little bluestem, indiangrass, orchardgrass, timothy
  • Weeds: Green foxtail, bristly foxtail, yellow nutsedge

This is a photo showing leaf streak on corn.

Photo: Jennifer Chaky

This is a photo showing leaf streak on corn.

Photo: Jennifer Chaky

Disease Management

  • Proper identification of the disease is crucial since it cannot be treated by chemical controls unlike many similar-appearing diseases.
  • Minimize continuous exposure to the crops and weeds that have been identified as susceptible hosts to bacterial leaf streak.
    • Control volunteer corn which can serve as a host.
    • Proper weed management and pasture grass control.
  • Harvest infected fields last to reduce the spread of inoculum.
  • Tillage and residue management are possible considerations.
  • There appears to be some variability among corn hybrids in susceptibility to bacterial leaf streak.

This is a photo showing bacterial leaf streak on a corn plant.

Photo: Mike Wardyn; near Elsie, NE June 26, 2018

References

Schlund, S., T. Hartman, T. Jackson-Ziems. 2017. Bacterial Leaf Streak of Corn. CropWatch. Lincoln, NE.

Robertson, A., K. Broders, R. French, T. Jackson-Ziems, D. Jardine, K. Korus, J. Lang, J. Leach. 2017. Bacterial Leaf Streak. Corn Disease Management. Crop Protection Network.


Author: Samantha Teten

June 2018

 

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The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.